CPT2: Principles of infectious disease management

Question 1

What is an AB?

What is a synthetic?

What is an Antimicrobial?

Answer 1

• Antibiotic – naturally occurring substance produced by micro-organisms that destroys or inhibits the growth of other micro-organisms e.g. penicillin
• Synthetic
• Antimicrobial – more strictly correct and refers to synthetic and natural agents

Question 2

What is:

• Commensal organisms
• Opportunistic infection
• Healthcare acquired infection (previously nosocomial, hospital infection)

Answer 2

Commensal organism:

Organism that usually grows in the body; inherently capable of causing infection, but do not do so in an immunocompetent host e.g. intestinal flora

Commensal organism in the wrong place can cause disease – e.g. E.coli from gut – bladder - UTI

Opportunistic infection:

• occur when the patient’s immune system is impaired – by another infection, disease or drugs.
• Infecting organism rarely causes disease in healthy individuals
• Immunocompromised patients: patients with HIV/AIDS, patients immunosuppressed due to cytotoxics

Healthcare accruired infection:

• Infections accquired in healthcare setting, include fungal & opportunistic bacterial infections.
• Very Resistant

Question 3

What is the difference between a sign and a symptom?

Answer 3

• A sign is an indication of an infection. It is observed by the health care professional, but is not necessarily apparent to the patient.
• A symptom is something that the patient does notice themselves.

Question 4

Signs and symptoms of infection

Answer 4

• Temperature >38C or <36C
  
  • Low indicative of sepsis
• Tachycardia (↑ pulse rate 90 beats/min), ↓BP
  
  • Low BP - sepsis?
• Respiratory rate >20/min
• Haematological signs: ↑WBC - ↑ neutrophil count, ↑ lymphocyte count, ↑ eosinophil count (less common)
• ↑ platelets
• Inflammatory markers – CRP, ESR
  
  • CRP raised in bacterial, not really viral
  • ESR long term, CPT acute
• LFTs, renal function
  
  • livertoxicity
• • specific signs/symptoms

Question 5

What are the goals of antimicrobal in acute infections?

Answer 5

• To eradicate infection by providing an optimal amount of active drug at the site of infection
• To prevent complication of disease – eg Meningitis and deafness
• To prevent supra infection – eg candida
  
  • Secondary

Question 6

What is the goal of antimicrobials in prophylaxis?

Answer 6

• To prevent infection – eg asplenic patients – Penicillin V to prevent pneumococcal infection
• To eradicate the carriage of a particular organism – eg MRSA
• To prevent the spread of a strain within a community – eg flu vaccine and prophylaxis

Question 7

What is narrow and borad spectrum anti-microbials?

Answer 7

• Narrow spectrum agents
  
  • Tend to only target 1 organism
  • fusidic acid
• •Broad spectrum agents
  
  • Tend to targt gram positive and negative

When choosing an antibacterial, ideally want to use as narrow a spectrum as possible to minimise the risk of resistance developing, but making sure that “most probable” organisms are targeted

Question 8

What are:

1. Bacteriostatic agents
2. Bactericial agents

Answer 8

• Bacteriostatic drugs prevent the growth of the organism with elimination ultimately depending on body defence mechanism
• Bactericidal drugs kill bacteria

Question 9

When is this important?

When should mode of action be looked into?

Answer 9

• only important in clinical situations where patients immune system response is depressed e.g. cancer patients undergoing chemotherapy, bactericidal agents should be chosen in preference; also when potentially life-threatening conditions such as infective endocarditis and meningitis.
• Mode of action – would be important to consider when dealing with potentially resistant strains eg TB, malaria. Would be important to combine drugs which have different modes of action to reduce potential of resistance – classification cell wall synthesis, protein synthesis, DNA synthesis